Beginning in 1979, men and women between the age of 14 and 22 were asked about their views on gender roles. Three more interviews were conducted with the same group between then and 2005, with a 60% retention rate of the 12,686 participants. This gave Timothy Judge and Beth Livingston of the University of Florida a large amount of data to work with.

Questions in the interviews included whether a woman’s place is in the home, and if a man should be the achiever outside of the home. Participants were also asked details such as their earnings, religious upbringing and education.

Controlling for different job types, hours worked and level of education, the researchers found that men with “traditional views” would take home an average of around $8,500 more than similar men who did not hold such views. With women, it turns out the opposite is true. Those who believed that they should be “stay-at-homes” earned $1,500 less a year than their “non-traditional” peers.

“These results show that changes in gender role attitudes have substantial effects on pay equity,” Judge said. “When workers’ attitudes become more traditional, women’s earnings relative to men suffer greatly. When attitudes become more egalitarian, the pay gap nearly disappears.”

The research also found some (fairly predictable) correlations with views on gender roles. People with parents who both worked held less traditional views, whilst married, religious people tended to be more traditional. As people grew older during the study, their views were also found to become more traditional.

In seeking an explanation for these results the researchers found that differences such as occupation or number of children were not a factor, so the findings could not be explained by the fact that in more traditional couples women were less likely to be working outside the home (and thus earn less). The conclusion was that the pay gaps do not just have an economic basis.

“Psychology has an important role to play, too,” said Judge. “Our country’s policies have been leaning toward gender equality for decades now. But, according to our study, traditional gender role views continue to work against this goal.”